I swapped in a lightning motor into my 2001 4.2L v6 truck.....i put in a single walbro 255 on the stock 4.2L fuel pump assembly. the fuel lines are also for the 4.2L....when i turn my truck on the fuel pressure drops from 40 to 15 and makes the engine run rough...what should i do get new fuel lines or the dual fuel pump assembly found in lightning...i was told that the walbro will give me plenty of fuel for my setup....